package business.search_eng.scorer;

/*		 
 * MG4J: Managing Gigabytes for Java
 *
 * Copyright (C) 2004-2009 Paolo Boldi and Sebastiano Vigna
 *
 *  This library is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as published by the Free
 *  Software Foundation; either version 2.1 of the License, or (at your option)
 *  any later version.
 *
 *  This library is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *  or FITfNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

import java.io.IOException;

import it.unimi.dsi.fastutil.ints.AbstractIntIterator;
import it.unimi.dsi.fastutil.objects.Reference2DoubleMap;
import it.unimi.dsi.fastutil.objects.Reference2DoubleMaps;
import it.unimi.dsi.mg4j.index.Index;
import it.unimi.dsi.mg4j.search.DocumentIterator;

/** An abstract implementation of {@link it.unimi.dsi.mg4j.search.score.Scorer}.
 * It provides internal caching of the underlying
 * document iterator during {@linkplain #wrap(DocumentIterator) wrapping},
 * and a complete implementation of the {@link it.unimi.dsi.fastutil.ints.IntIterator}
 * methods by delegation to the underlying document iterator (implementing subclasses
 * that do not alter this behaviour should implement {@link it.unimi.dsi.mg4j.search.score.DelegatingScorer}). 
 * The {@link #setWeights(Reference2DoubleMap)}
 * method simply returns false.
 * 
 */
public abstract class AbstractScorer extends AbstractIntIterator implements Scorer {
	/** The current document iterator. */
	protected DocumentIterator documentIterator;
			
	/** Wraps the given document iterator.
	 * 
	 * <p>This method {@linkplain #documentIterator records internally the provided iterator}.
	 * 
	 * @param documentIterator the document iterator that will be used in subsequent calls to
	 * {@link #score()} and {@link #score(Index)}. 
	 */
	
	public void wrap( final DocumentIterator documentIterator ) throws IOException {
		this.documentIterator = documentIterator;
	}

	/** Returns false. */
	
	public boolean setWeights( final Reference2DoubleMap<Index> index2Weight ) {
		return false;
	}
	
	/** Returns an empty map. */
	@SuppressWarnings("unchecked")
	public Reference2DoubleMap<Index>  getWeights() {
		return Reference2DoubleMaps.EMPTY_MAP;
	}
	
	@Deprecated
	public int nextInt() {
		return documentIterator.nextInt();
	}

	public int nextDocument() throws IOException {
		return documentIterator.nextDocument();
	}

	public int skip( final int n ) {
		return documentIterator.skip( n );
	}

	public boolean hasNext() {
		return documentIterator.hasNext();
	}
}
